mtd: nand: sunxi: fix potential divide-by-zero error

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=791eccd94965a8029ae09c5530bcb9a76794e408
Commit:     791eccd94965a8029ae09c5530bcb9a76794e408
Parent:     f7f8c1756e9a5f1258a7cc6b663f8451b724900f
Author:     Bryan O'Donoghue <pure.logic at nexus-software.ie>
AuthorDate: Fri Jul 28 14:22:57 2017 +0100
Committer:  Boris Brezillon <boris.brezillon at free-electrons.com>
CommitDate: Wed Aug 2 10:26:40 2017 +0200

    mtd: nand: sunxi: fix potential divide-by-zero error
    
    clk_round_rate() can return <= 0. Currently the value returned by
    clk_round_rate() is used directly for a division. This patch introduces a
    guard to ensure a divide-by-zero or a divide by a negative number for that
    matter can't happen by bugging out returning -EINVAL if clk_round_rate()
    returns <= 0.
    
    Fixes: 2d43457f79e4 ("mtd: nand: sunxi: fix EDO mode selection")
    Signed-off-by: Bryan O'Donoghue <pure.logic at nexus-software.ie>
    Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/mtd/nand/sunxi_nand.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index d0b6f8f..6abd142 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1728,6 +1728,10 @@ static int sunxi_nfc_setup_data_interface(struct mtd_info *mtd, int csline,
 	 */
 	chip->clk_rate = NSEC_PER_SEC / min_clk_period;
 	real_clk_rate = clk_round_rate(nfc->mod_clk, chip->clk_rate);
+	if (real_clk_rate <= 0) {
+		dev_err(nfc->dev, "Unable to round clk %lu\n", chip->clk_rate);
+		return -EINVAL;
+	}
 
 	/*
 	 * ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data